This invention is related to a process for limiting the speed of an externally ignited, internal combustion engine and a device for performing the process.
The presently known processes for limiting the speed of externally ignited combustion engines have various disadvantages which affect the driveability and the exhaust characteristics of the vehicle being powered by said engine. For example shutting off of the fuel supply when reaching a predetermined highest speed can result in dangerous conditions if it occurs while another vehicle is being passed. Furthermore if the fuel is shut off while high acceleration is taking place in a low gear, it results in a high braking force on the vehicle. The same is true if the engine speed is limited by interrupting the ignition circuit.
It is further known from German Pat. DE-OS No. 24 14 298 that another method of speed limiting comprises eliminating alternate ignition pulses when a predetermined high speed is reached thereby eliminating the abrupt shutting off of the combustion engine. However, this results in a rough running of the engine which in turn causes excessive stresses on the transmission elements such as, for example, the drive shaft. Furthermore if the combustion engine is provided with an exhaust gas catalyst, the danger of overheating the catalyst exists because of the combustion of the unburned fuel which comprise the exhaust gases.